This invention relates to a device for testing lung function.
Presently available devices for this purpose are the spirometer which is used to record certain standard measurements, including forced expiratory volume in one second (FEV.sub.1) and forced vital capacity (FVC), and the Wright peak flow meter, which measures the peak expiratory flow rate (PEFR). FEV.sub.1 is the maximum volume of air that is possible for the patient to blow out in 1 second having breathed in as deeply as possible to maximum inspiratory capacity. FVC is the total volume of air that can be breathed out after breathing in to maximum inspiratory capacity.
Such known instruments suffer from the disadvantages of high cost and lack of portability. While they are capable of great accuracy and are necessary if precise quantitative measurements are required, yet there exists a need for an inexpensive and portable device suitable for use in general medical practice, for example in the observation and treatment of asthma sufferers.
Such a device ideally should be sufficiently inexpensive, portable, and easy to use as to be feasibly prescribed for patients to use at home.